# diskcheck(1)

## NAME

         diskcheck - check a disk for bad sectors

## SYNOPSIS

         diskcheck device start count

## EXAMPLES

         diskcheck /dev/at0 0 1200
                             # Check 1.2 MB diskette

         diskcheck /dev/at0 100 50
                             # Check blocks 100 to 149

## DESCRIPTION

         Diskcheck checks a disk for  bad  sectors  by  reading  in  each  sector,
         writing  a  known  bit  pattern onto it, reading it back in and comparing
         with what was written.  This check is  then  done  a  second  time.   Bad
         sectors  are  reported.  After each sector is tested, the original sector
         is restored.  Only use this program on unmounted partitions.  Killing  it
         part way through may result in lost data.

## SEE ALSO

         format(1).